Valve flow control optimization via customization of an intelligent actuator

ABSTRACT

A valve arrangement including a valve and a valve actuation arrangement is provided. The valve has a known flow profile. The valve includes a valve member and a valve stem operably coupled to the valve member for adjusting the position of the valve member. The valve actuation arrangement is operably coupled to the valve stem. The valve actuation arrangement includes a drive arrangement and a control arrangement. The drive arrangement is operably coupled to the valve stem and configured to adjust an actual stem position of the valve stem based on an actual stem positional signal. The control arrangement is configured to generate the actual stem positional signal. The control arrangement is configured to generate the actual stem positional signal based on an input control signal representing a desired stem position based on a desired flow profile being different than the known flow profile.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application for patent is a continuation of U.S. application Ser.No. 14/296,024, filed Jun. 4, 2014, which is a continuation ofInternational Application No. PCT/US2011/067910, filed Dec. 29, 2011,the entire teachings and disclosure of the foregoing applications beingincorporated herein by reference thereto. This application is alsorelated in subject matter to and incorporates herein by referencecommonly-assigned U.S. application Ser. No. 15/847,963 entitled “ValveFlow Control Optimization Via Customization of an Intelligent Actuator”filed concurrently herewith.

FIELD OF THE INVENTION

This invention generally relates to valve actuators for controlling theopening and closing of valves to control a flow rate of fluid throughthe valve and associated systems.

BACKGROUND OF THE INVENTION

Valves are used to adjust the fluid flow through a system. Oneparticular system where valves are used to control fluid flow are inheating, ventilating and air-conditioning systems (HVAC systems). Forinstance, liquid valves may be used to regulate water flowing through aheating system or valves in the form of dampers may be used to regulatecooled or heated air into an environment that is being conditioned.

At present, most HVAC systems have HVAC control systems that include endcontrol devices, such as valve actuators, that control mechanicaladjustment of end control elements, such as valves, in response to acontrol signal from an HVAC controller or building management system(BMS). Typically, a control signal is sent to the valve actuator and thevalve actuator adjusts its output to change the position of the valvemember of the valve (or damper) between a closed or open position in anopen-close, floating, or modulating control manner. It is assumed thatthese changes in position of the end control element will result in achange in energy delivered to a controlled zone (via chilled or hotwater heat transfer or conditioned air).

Unfortunately, valves do not have the same flow response curve from onetype or size of valve to another type or size of valve. The same appliesto dampers. Therefore, not all valves provide exactly the same flow vs.controlled valve position. Many HVAC control systems base their controlsignal that is sent to the valve actuator as if the valve has a flowprofile that is an equal percentage flow curve. Unfortunately, becausemany, if not most, valves do not have a same flow profile andparticularly not a flow profile that follows the equal percentage flowcurve, tremendous amounts of error in controlling the flow of the valveexists.

For instance, for an equal percentage flow curve, the control systemwill typically expect about a 15% valve flow as a percentage of valverated flow (Cv or Kv) when the valve is at a 50% valve position (i.e.half way between open and closed). In some families of valves (i.e. samestyle valve just change in valve size), the actual valve flow as apercentage of valve rated flow at the 50% valve position can rangebetween 6% and 60% depending on the valve size. This variation fromvalve to valve can provide a significant error in the system consideringthe high accuracy of the command to the valve actuator from the HVACcontroller.

These inherent errors from the theoretical flow curve (typically theequal percentage flow curve) can often cause system designers tooversize valves to insure that the system can provide enough flow rateunder all conditions. This is because an undersized valve can neverprovide enough flow, and consequently carry enough energy, to meet allapplication needs. This habitual over sizing of the valves tends tocause the need for larger pumps, requiring more energy to supply theheating/cooling needs of the facility. Larger valves also tend torequire larger heater radiator coils, raising the costs to install theactual HVAC system.

A further problem relating to oversized valves or significant errorbetween the theoretical flow profile used by the HVAC control system andthe actual flow profile of the valve is that the HVAC control system maycause significant overshoot in the control of the HVAC system such thatthe system cycles back and forth between high levels of heating followedby high levels of cooling to provide the desired conditioning of a zone.While the high level HVAC control systems may have sufficient feedbackcontrol to properly heat or cool the zone or environment, the systemwill be continuously fighting against itself causing inefficientoperation of the HVAC system.

BRIEF SUMMARY OF THE INVENTION

Embodiments of the present invention allow for more intelligent controlof a valve based on the known flow profile of the valve. The methods andapparatuses here allow for correlation of an input control signal basedon a desired flow profile to an actual valve stem positional signalbased on the known flow profile of the valve being controlled.

In a particular method according to an embodiment of the presentinvention, a method of operating a valve actuator arrangement for avalve having a known flow profile is provided. The method includesreceiving a first input control signal representing a first desired stemposition based on a first desired flow profile, the first desired flowprofile being different than the known flow profile, the first desiredstem position having a corresponding first theoretical stem positionalsignal and a corresponding first theoretical flow rate; and generatingan actual first stem positional signal different than the firsttheoretical stem positional signal corresponding to an actual first stemposition providing the first theoretical flow rate based on the knownflow profile.

In an embodiment of the method, the method further comprises providingthe actual stem positional signal to an actuation arrangement anddriving the actuation arrangement based on the actual stem positionalsignal.

In one embodiment, the desired flow profile is selected from the groupconsisting of an equal percentage flow profile, a fast acting flowprofile, and a linear flow profile. It could also be an equal percentagemodified flow profile.

In one embodiment, the desired flow profile is a user custom definedflow profile. In one embodiment, the user defined flow profile isselected from the group consisting of A) a reduced rate flow profile isa flow profile reduced by a percentage reduction factor such that thereduced rate profile is less than a full flow capability of the valveand B) a flow limiting profile that is a flow profile capped at a lessthan a full flow capability.

In another embodiment, the method allows for switching between modesusing different correlation mechanisms such as between different knownflow profiles for different valves or for different desired flowprofiles. The method further includes receiving a second input controlsignal representing a second desired stem position based on a seconddesired flow profile, the second desired flow profile being differentthan the known flow profile and the first desired flow profile, thesecond desired stem position having a corresponding second theoreticalstem positional signal and a corresponding second theoretical flow rate;and generating an actual second stem positional signal different thanthe second theoretical stem positional signal corresponding to an actualsecond stem position providing the second theoretical flow rate based onthe known flow profile.

In a more particular implementation, the steps of:

receiving a first input control signal representing a first desired stemposition based on a first desired flow profile, the first desired flowprofile being different than the known flow profile, the first desiredstem position having a corresponding first theoretical stem positionalsignal and a corresponding first theoretical flow rate; and

generating an actual first stem positional signal different than thefirst theoretical stem positional signal corresponding to an actualfirst stem position providing the first theoretical flow rate based onthe known flow profile;

occur during a first mode. The steps of:

receiving a second input control signal representing a second desiredstem position based on a second desired flow profile, the second desiredflow profile being different than the known flow profile and the firstdesired flow profile, the second desired stem position having acorresponding second theoretical stem positional signal and acorresponding second theoretical flow rate;

generating an actual second stem positional signal different than thesecond theoretical stem positional signal corresponding to an actualsecond stem position providing the second theoretical flow rate based onthe known flow profile;

occur during a second mode. The method further comprising switching fromthe first mode to the second mode.

In another embodiment, the step of:

generating an actual first stem positional signal different than thefirst theoretical stem positional signal corresponding to an actualfirst stem position providing the first theoretical flow rate based onthe known flow profile;

includes using a first lookup table or equivalent mathematical equationcorrelating the first input control signal to the actual first stempositional signal to determine the actual first stem positional signal.Step of:

generating an actual second stem positional signal different than thesecond theoretical stem positional signal corresponding to an actualsecond stem position providing the second theoretical flow rate based onthe known flow profile;

includes using a second lookup table or equivalent mathematical equationcorrelating the second input control signal to the actual second stempositional signal to determine the actual second stem positional signal.

In one embodiment, the first and second lookup tables or equivalentmathematical equations are stored in the valve actuation arrangement ata same time. The method further includes switching from the second modeto the first mode.

In one embodiment, the step of generating an actual first stempositional signal includes correlating the first input control signal tothe actual first stem positional signal.

In one embodiment, correlating the first input control signal to theactual first stem positional signal includes using a lookup table orequivalent mathematical equation.

In one embodiment, the step of generating an actual first stempositional signal includes correlating the first input control signal tothe actual first stem positional signal; and the step of generating anactual second stem positional signal includes correlating the secondinput control signal to the actual second stem positional signal.

In one embodiment of the invention, a valve arrangement including avalve and a valve actuation arrangement is provided. The valve has aknown flow profile. The valve includes a valve member and a valve stemoperably coupled to the valve member for adjusting the position of thevalve member. The valve actuation arrangement is operably coupled to thevalve stem. The valve actuation arrangement includes a drive arrangementand a control arrangement. The drive arrangement is operably coupled tothe valve stem and configured to adjust an actual stem position of thevalve stem based on an actual stem positional signal. The controlarrangement is configured to generate the actual stem positional signal.The control arrangement is configured to generate the actual stempositional signal based on an input control signal representing adesired stem position based on a desired flow profile being differentthan the known flow profile.

In one embodiment, the known flow profile is different than the desiredflow profile in that in at least one same valve stem position for theknown and desired flow profiles each flow profile has a different flowrate.

In one embodiment, the desired flow profile is an equal percentage flowprofile.

In one embodiment, the control arrangement includes a lookup table orequivalent mathematical equation that correlates the input controlsignal to the actual stem positional signal.

In one embodiment, the valve actuation arrangement includes a mastercontroller, an intermediate signal translator device and a valveactuator including the drive arrangement. The intermediate signaltranslator device is interposed between the master controller. Themaster controller is configured to generate the input control signal.The intermediate signal translator is configured to generate the actualstem positional signal based on the input control signal from the mastercontroller.

In one embodiment, the master controller has an output interface. Thevalve actuator has an input interface. The intermediate signaltranslator has an input interface coupled to the output interface of themaster controller. The intermediate signal translator has an outputinterface coupled to the input interface of the valve actuator. Thevalve actuator is packaged as a first unit. The intermediate signaltranslator is packaged as a second unit independent of the first unit.This allows for retrofit in existing systems.

In one embodiment, the intermediate signal translator is programmed witha lookup table or equivalent mathematical equation configured tocorrelate the input control signal to the actual stem positional signal.

In one embodiment, the control arrangement is further configured togenerate the actual stem positional signal based on a second inputcontrol signal representing a second desired stem position based on asecond desired flow profile being different than the known flow profileand different than the first desired flow profile.

In one embodiment, the control arrangement is switchable betweengenerating the actual stem positional signal based on the desired flowprofile and generating the actual stem positional signal based on thesecond desired flow profile.

In one embodiment, the control arrangement is configured to correlatethe input control signal to the actual stem positional signal using afirst lookup table or equivalent mathematical equation and configured tocorrelate the second input control signal to the actual stem positionalsignal using a second lookup table or equivalent mathematical equationdifferent than the first lookup table or equivalent mathematicalequation.

In one embodiment, the control arrangement is configured correlate theinput control signal to the actual stem positional signal using a lookuptable or equivalent mathematical equation.

In one embodiment, the control arrangement includes a master controllerand a valve actuator operably coupled to the master controller. Thevalve actuator includes the drive arrangement. The valve actuator ispackaged as a first unit. The master controller is packaged as a secondunit independent of the first unit. The master controller configured togenerate the input control signal and then correlate the input controlsignal to the actual stem positional signal.

In one embodiment, the control arrangement includes a master controllerand a valve actuator. The valve actuator includes an actuator controlleroperably coupled to the master controller. The valve actuator ispackaged as a first unit including the actuator controller and the drivearrangement. The master controller is packaged as a second unitindependent of the first unit. The master controller is configured togenerate the input control signal and the actuator controller isconfigured to receive the input control signal and correlate the inputcontrol signal to the actual stem positional signal.

In another embodiment, a valve actuation arrangement operably couplableto a valve having a known flow profile is provided. The valve includes avalve member and a valve stem operably coupled to the valve member foradjusting the position of the valve member. The valve actuationarrangement includes a drive arrangement and a control arrangement. Thedrive arrangement is operably couplable to the valve stem and configuredto adjust an actual stem position of the valve stem based on an actualstem positional signal. The control arrangement is configured togenerate the actual stem positional signal to control operation of thedrive arrangement. The control arrangement is configured to generate theactual stem positional signal based on an input control signalrepresenting a desired stem position based on a desired flow profilebeing different than the known flow profile.

In another embodiment, a method of programming a valve actuationarrangement for a valve having a known flow profile is provided. Themethod includes obtaining a correlation table correlating an inputcontrol signal representing a desired stem position based on a desiredflow profile with an actual stem positional signal based on the knownflow profile. The desired flow profile being different than the knownflow profile. The method further includes storing the correlation tablein the valve actuation arrangement.

In a more particular method, the method includes sending a valveidentifier identifying the valve to a host; sending a desired flowprofile identifier to the host; and receiving the correlation table.

The method may further include obtaining a second correlation/lookuptable or equivalent mathematical equation correlating an input controlsignal representing a second desired stem position based on a seconddesired flow profile with an actual stem positional signal based on theknown flow profile. The second desired flow profile is different thanthe known flow profile and the desired flow profile. The method furtherincluding storing the second correlation table in the valve actuationarrangement.

Preferably, the correlation table and second correlation table are bothstored in the valve actuation arrangement.

In another method, a method of generating a correlation tablecorrelating an input control signal to an actual stem position signalfor a valve having a known flow profile is provided. The method includesreceiving a valve identifier identifying a valve, the valve having aknown flow profile from a user; receiving a desired flow profileidentifier from a user; and generating a correlation table correlatingan input control signal representing a desired stem position based onthe desired flow profile with an actual stem positional signal based onthe known flow profile, the desired flow profile being different thanthe known flow profile; and sending the correlation table to the user.

The method may further include receiving a desired flow profileidentifier includes receiving user defined desired flow profileinformation.

A further method of controlling a valve actuator for a valve having aknown flow profile is provided. The method includes receiving an inputcontrol signal representing a desired flow output based on a desiredflow profile, the desired flow profile being different than the knownflow profile; correlating the desired flow output to a known stempositional signal that will produce the desired flow output; andgenerating the known stem positional signal.

Other aspects, objectives and advantages of the invention will becomemore apparent from the following detailed description when taken inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings incorporated in and forming a part of thespecification illustrate several aspects of the present invention and,together with the description, serve to explain the principles of theinvention. In the drawings:

FIG. 1 is a schematic illustration of an HVAC system using a valve andvalve actuation arrangement according to embodiments of the presentinvention;

FIG. 2 is a schematic illustration of an HVAC system using a valve and asecond embodiment of an actuation arrangement according to the presentinvention;

FIG. 3 is a plot of theoretical flow profiles used for mastercontrollers;

FIG. 4 is a plot of actual flow profiles for known valves;

FIG. 5 is a plot showing how the valve actuation arrangements can causea valve having a known profile to emulate a desired flow profile;

FIG. 6 is a chart showing how to correlate a control input signal to adesired stem positional signal;

FIG. 7 is a plot of a modified valve response curve;

FIGS. 8 and 9 are examples of user defined desired flow profiles;

FIG. 10 is a schematic representation of how a user can reprogram avalve actuation arrangement according to the present invention; and

FIG. 11 is a schematic illustration of an HVAC system using a valve anda third embodiment of an actuation arrangement according to the presentinvention.

While the invention will be described in connection with certainpreferred embodiments, there is no intent to limit it to thoseembodiments. On the contrary, the intent is to cover all alternatives,modifications and equivalents as included within the spirit and scope ofthe invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates a simplified schematic illustration of a HVAC system100 used to condition an environment 102 according to embodiments of thepresent invention. The HVAC system 100 could use either flowing water orair as a fluid for conditioning environment 102.

The HVAC system 100 includes a fluid source 113 and a pump 106 forpumping the fluid used to condition the environment 102. A valve 108 isinterposed between the fluid source 113 and the environment to controlthe flow of the fluid toward the environment and particularly to alocation where the fluid is used to condition the environment. Forinstance, in FIG. 1, the valve 108 controls flow of water to a radiator110 or other heat transfer device for cooling or heating the environment102. In such an embodiment, the valve 108 could take the form of a waterflow control valve and the fluid source 113 could include heating coilsfor heating the water prior to being passed to radiator 110. Inalternative embodiments, the valve 108 could take the form of a damperand the fluid source 113 could be a furnace or air-conditioner while theoutlet (i.e. radiator 110) could be in the form of a vent in fluidcommunication with the environment.

While not illustrated, the HVAC system 100 could have different zonesthat are all supplied with fluid from the fluid source 113.

To control operation of the valve 108, the HVAC system 100 includes avalve actuation arrangement 112 operably coupled to the valve 108. Inthe illustrated embodiment, the valve actuation arrangement 112 isoperably coupled to a valve stem 114 that is operably coupled to a valvemember 116 of the valve. Movement of the valve stem 114 operably movesthe valve member 116 relative to a valve body 118. Movement of the valvemember 116 adjusts the amount of flow permitted through the valve 108between a minimum flow (typically no flow) and a maximum flow. The valvestem 114 may rotate the valve member 116 about a rotational axis,axially move the valve member 116 along a linear axis, may open andclose louvers or other members if the valve 108 is in the form of adamper, etc. The valve 108 will have a known flow profile 148 (see FIG.5) that relates fluid flow relative to stem position. In FIG. 5, theflow profile 148 of a valve 108 is expressed in terms of percentage ofmaximum flow as a function of percentage of full stroke.

In the embodiment of FIG. 1, the valve actuation arrangement 112includes a valve actuator 122 operably coupled to the valve 108 thatphysically controls motion of the valve stem 114, and consequently, thevalve member 116. The valve actuator 122 includes a drive mechanism 124that can include, at a minimum, a drive motor for driving the valve stem114. The drive mechanism 124 may also include gears and/or atransmission for translating an output of the motor to the valve stem114. A coupling 126 is provided between the motor and/or transmission ofthe valve actuator 122 and the valve stem 114 to assist in operablycoupling the valve actuator 122 to the valve stem 114. The valveactuator 112 and typically the drive mechanism may include electroniccontrol mechanisms (which may include a microprocessor and some storagemedia) for controlling the motor to operably drive the valve stem 114,and consequently the connected valve member 116 relative to the valvebody 118, in response to an actual stem positional signal. Theelectronics associated with the drive mechanism 124 may allow forparticularly positioning the valve stem 114 between opposed ends of thefull stroke of the valve 108. In some embodiments, the drive mechanismis in the form of a stepper motor that separates the full stroke intoindependent equal sized steps. Alternatively, the drive mechanisms caninclude a synchronous motor or DC motor controlled by timing.

The valve actuator 122, in the illustrated embodiment, also include anactuator controller 128 operably coupled to the drive mechanism 124operably configured to generate the actual stem positional signal. Theactuator controller 128 of the illustrated embodiment is configured toreceive an input control signal from a master controller 130. Theactuator controller 128 may include a microprocessor and storage media.The drive mechanism 124 controls the valve stem based on this actualstem positional signal sent from the actuator controller 128.

The master controller 130 is operably configured to generate the inputcontrol signal that is operably used to control positioning of the valvestem 114 to a specific position. This specific position is intended toproperly adjust fluid flow through the valve 108 to adjust the amount ofconditioning that occurs within the environment 102, for example, theamount energy added during a heating operation. Typically, the mastercontroller 130 will be operably connected to a sensor 131 within theenvironment 102 to allow the master controller 130 to determine how toadjust control of the HVAC system 100 to properly condition environment102. Typically, sensor 131 will be a temperature sensor positionedwithin the environment 102. The sensor 131 may also be or include othersensors for sensing humidity within the environment 102. Further, themaster controller 130 may control an HVAC system for an entire buildingthat has multiple zones for different environments, such as differentrooms, floors, etc. Thus, the master controller 130 may communicate withnumerous sensors.

Typically, the master controller 130 will be programmed to generate theinput control signal based on a theoretical flow profile of a desiredvalve controlling the fluid flow. FIG. 3 is a plot of theoretical flowprofiles that are generally used for programming master controllers 130.Flow profile 134 is an equal percentage flow profile (hereinafter “equalpercentage flow profile 134”). Flow profile 136 is a fast acting flowprofile (hereinafter “fast acting flow profile 136”). Flow profile 138is a linear flow profile (hereinafter “linear flow profile 138”).

Ideally programming of the master controller 130 will typically use atheoretical flow profile, such as one of these flow profiles 134, 136,138, or other theoretical flow profile, that the programmer believesbest approximates the actual flow profile of the valve within the HVACsystem. This allows the end program to correctly determine the desiredposition of the valve stem so as to provide the expected amount of fluidflow.

In this embodiment, the actuator controller 128 may individually beconsidered or may be in combination a control arrangement configured togenerate the actual stem positional signal, with the actual stempositional signal being based on the input control signal representingthe desired stem position based on the desired flow profile.

FIG. 4 illustrates that, unfortunately, even within a line of similarlydesigned valves (varying typically only in size), the flow profilesthereof do not always maintain a common shape. FIG. 4 plots first,second and third known flow profiles 140, 142, 144 for different valveswithin a single product line but merely having different valve sizes(i.e. full flow capacities) in addition to the equal percentage flowprofile 134 discussed above. It can be seen that there is significantvariation between the three different known flow profiles 140, 142, 144as well as equal percentage flow profile 134. The significant variationfrom the theoretical flow profile, i.e. the equal percentage flowprofile 134 in this example, provides significant error in the systemwhen the master controller 130 is programmed to generate an inputcontrol signal based on a theoretical flow profile that does not matchor come close to matching the actual flow profile of the valve beingcontrolled.

With reference to FIG. 4, if the master controller 130 determined, forexample, that it needed to generate a valve stem positional signal of50% of full stroke, significantly different percentage flow rates wouldbe generated depending on which valve was being controlled. A true equalpercentage flow profile would have a percentage flow rate ofapproximately 15% and in the lowest case, first known flow profile 140would have a percentage flow rate of approximately 6% while in thehighest case, third known flow profile 140 would have a percentage flowrate of approximately 60%. As can be seen, there will be a significantdifference and significant error in the actual amount of energy thatwill be transferred to or from the environment in view of the variationin the flow profiles between different valves.

It should be noted that while FIG. 4 illustrates that there is largevariation from one valve size to another, there is typically much lessvariation between individual valves of a same exact size. As such, whena flow profile of a given valve is determined, the rest of the valvessimilarly configured should have substantially the same flow profile.

Embodiments of the present invention provide intelligent control to thevalve actuation arrangement 112 that allows for specific tailoring ofthe valve actuation arrangement 112 based on the known flow profile ofthe specific valve 108 coupled to the valve actuation arrangement 112,and at a minimum the particular valve actuator 122 of the valveactuation arrangement 112 controlling the particular valve 108.

With additional reference to FIG. 5, in one embodiment, such as in FIG.1, the actuator controller 128 of the valve actuator 122 is configuredsuch that it can be user programmed based on the known flow profile 148of valve 108 that the valve actuator 122 is controlling such that thevalve 108 will emulate that of a desired flow profile, such as equalpercentage profile 134. Therefore, when the actuator controller 128receives an input control signal from the master controller 130representing a desired stem position based on the desired flow profileused by the programming of the master controller 130, i.e. the equalpercentage flow profile 134 for example, the actuator controller 128will correlate that input control signal to an actual stem positionalsignal that represents a different actual stem position than the desiredstem position. The actuator controller 128 will then generate the actualstem positional signal that will control the drive arrangement 124 toposition the valve stem 114 in the proper orientation and provide thedesired percentage flow rate.

More particularly, the actuator controller 128 is configured to generatean actual valve stem positional signal that will place the valve stem114 of the valve 108 in the proper position to provide the desired flowrate that corresponds to the desired stem position.

Typically, the input control signal from the master controller 130 is alinear analog signal. In some embodiments, the linear signal is a linearvoltage signal between 0 and 10 volts DC or a linear current signalbetween 4 and 20 mA. In some embodiments, this signal could be adigital, such as via a communications network.

In FIG. 5, a theoretical response curve 150 is plotted which illustratesthe theoretical response curve that the master controller 130 isprogrammed to believe the actuator will exhibit based on the linearinput control signal generated by the master controller 130. Moreparticularly, theoretical response curve 150 represents the inputvoltage as a function of percentage of valve stem position.

In one embodiment, the actuator controller 128 will be programmed to usea lookup table or equivalent mathematical equation that correlates theinput control signal sent from the master controller 130 based on thetheoretical desired flow profile underlying the programming of themaster controller 130 to the actual stem positional signal thatrepresents the same flow rate based on the known flow profile 148 ofvalve 108. Again, the known flow profile 148 of the valve 108 istypically different than the desired flow profile 134. However, theactuator controller 128 may use other mechanisms or programming toperform the correlation. The actuator controller 128 will then generatethe actual stem positional signal which corresponds to the actual stemposition necessary to provide the theoretical flow rate the mastercontroller 130 based on the actual known flow profile 148 of the valve108. This signal is then sent to the drive arrangement 126. Anequivalent mathematical equation to a lookup table can be generated, inone way, by generating the data points of the lookup table and thenfitting a curve to the data points and generating a regression equation.While following embodiments may be discussed interims only of a lookuptable generally, these embodiments could also use an equivalentmathematical equation instead.

FIG. 6 illustrates one method of generating the data for the lookuptable for correlating the input control signal sent from the mastercontroller 130 to the actual stem positional signal that is used tocontrol the drive mechanism 124.

Each input control signal represents a desired valve stem position andthus a desired flow rate. This desired valve stem position isrepresented by vertical line 152. For this example, we will use adesired valve stem position of 50%. The intersection 154 of the verticalline 152 at the desired valve stem position and the linear theoreticalresponse curve 150, which the programming of the master controller isbased, determines the value of the input control signal for that desiredvalve stem position. In this instance, the input control signal from themaster controller 130 would be 5.0 volts.

Next, the desired theoretical flow rate is determined based on thisvalve stem position. The intersection 156 of the vertical line 152 andthe desired flow profile, i.e. equal percentage flow profile 134,identifies the desired percentage flow rate based on equal percentageflow profile 134 for the stem position and input control signal. In thisinstance, the desired percentage flow rate for the input control voltageof 5.0 volts is approximately 15%.

Next, the desired percentage flow rate of 15% is used to determine theactual valve stem position required for valve 108 based on its knownflow profile 148. This actual valve stem position value is identified atthe intersection 157 of horizontal line 158 representing the desiredpercentage flow rate of 15% and the known flow profile 148 for valve108. In this example, the actual valve stem position is approximately33%. Next, the actual stem positional signal that must be generated toposition the valve stem 114 of the valve 108 in the proper actual stemposition of 33% is determined. This actual stem positional signal isidentified at the intersection 159 of vertical line 160 and the linearresponse curve 150. At this location, it is determined that an actualstem positional signal of approximately 3.3 volts is necessary toposition the valve stem 114 of valve 108 in the proper position for itto provide the desired flow rate. This can be repeated for all desiredstem positions of the desired flow curve 134 to generate the lookuptable and a modified actuator response curve.

FIG. 7 illustrates a plot of the data that would be in the lookup tablefor the valve 108 having the known flow profile 148 if it is desired tohave the valve 108 emulate an equal percentage valve using the priorsteps.

Plot 162 represents the reprogrammed actuator response curve. Plot 162is a plot of actual valve stem position signal (y-axis) as a function ofthe input control signal (x-axis). Once this plot 162 or a correspondinglookup table having sufficient data points along plot 162 is generatedfor a given configuration, i.e. a particular valve having a known flowprofile and a particular desired flow profile on which the programmingof the master controller 130 is premised, any input control signal valuecan be easily correlated to the actual valve stem positional signalnecessary to control drive mechanism 124. Again, in the illustratedembodiment, this correlation is performed by the actuator controller128. From FIG. 7 and plot 162 therein, it can be seen that thereprogrammed actuator response curve 162 is non-linear.

Using the above system, valve 108 can be configured to emulateessentially any desired flow profile, as long as the flow profile doesnot have a maximum flow that is greater than the maximum flow of valve108.

FIG. 8 illustrates a flow limiting profile 164. A flow limiting profilelimits the maximum flow of a valve to some flow that is less than thefull Cv/Kv of the valve. In the illustrated embodiment, the flowlimiting profile 164 is a limited equal percentage curve that is cappedat 70% maximum flow. More particularly, once the flow limiting profile164 reaches 70% of maximum flow, the flow limiting profile 164 includesa horizontal section 166. In practice, this flow profile is useful tolimit the maximum flow through one loop of an HVAC system in order toallow enough flow to other loops in a building while still providing anequal percentage flow profile related to the valves rated Cv/Kv. Themaximum flow rate could be electronically readjusted based on varyingapplication needs.

FIG. 9 illustrates a reduced rate flow profile 168. A reduced flow rateflow profile is given desired flow profile reduced by a percentagereduction factor such that the reduced rate flow profile is less than afull flow capability of the valve but still maintains substantially thesame shape. In this embodiment, the reduced rate flow profile 168 is areduced rate equal percentage flow profile. More particularly, thereduced rate flow profile 168 is equal percentage flow profile 134multiplied by a constant percentage reduction factor of 70%. Thisconfiguration allows the flow profile to emulate an equal percentageflow profile over the valves full range, but at a reduced rate. Inpractice, this allows for the emulation of an oversized valve to alesser flow Cv/Kv utilizing the reduced rate flow profile 168.

Both the flow limiting profile and the reduced rate flow profiles abovecould be applied to different theoretical curves, such as linear,fast-acting, etc.

The use of the system and information above allows for fully userdefined flow profiles. A user can generate a user defined flow profileand then cause a valve to emulate the user defined flow profile bygenerate a reprogrammed actuator response curve that will allow thevalve to emulate the desired flow profile.

Valve actuator 122 is preferably user programmable. More particularly,the valve actuator 122 is configured such that the user can reprogramthe actuator controller 128. For instance, in the event that theactuator 122 is applied to a different type of valve, the user couldreprogram the actuator controller 128, and particularly the correlationmechanism, i.e. lookup table, based on the known flow profile for thenew valve. Similarly, if the same valve is being used, but the userdecides to emulate a different desired flow profile, the user couldreprogram the actuator controller 128 by providing, e.g. a new lookuptable based on the known profile of the valve and the new desired flowprofile.

FIG. 10 expands on the reprogramability feature. In this illustration,valve 108 includes a valve ID tag 172 that stores or representsparticular information of the valve 108, such as valve part number,revision number, flow rating, production date, etc. The user can obtainthe valve identification information from the valve 108, illustrated byarrow 174. The user can then use the valve identification information torequest valve flow profile data from a database 180, such as a databaseprovided by the manufacturer, over a network 178 such as the internet.The user 170 could request specific desired flow profiles or generate auser defined flow profile and the correlation mechanism, i.e. lookuptable, for the specific valve and the desired flow profile, can then besent back to the user over the network 178, illustrated by arrows 182.The user can then upload the new correlation mechanism to the actuatorcontroller 128, illustrated by arrow 184, to reprogram the valveactuator 122.

In some embodiments, it is desirable for the valve actuator 122 to beable to store different correlation mechanisms, i.e. different lookuptables, at one time. This allows a user to switch between differentpreprogrammed configurations, i.e. each different lookup table, duringinitial setup of if system modifications are needed. For instance, ifwhile field testing an HVAC system, it is determined that one zone ofthe HVAC system is not operating properly, the user can immediatelyswitch between different modes to attempt to troubleshoot the systemwithout being required to access new correlation mechanisms.

The use of these intelligent actuators allows for controlling low costvalves in desired ways and more accurately.

In one embodiment, the systems do not use fluid flow feedback. Moreparticularly, actual flow through the valve 108 or pressure drop acrossthe valve 108 is not directly used to program or reprogram the actuatorcontroller 128 or even to control the positioning of the valve stem 114.Instead, the positioning of the valve stem 114 to obtain a desired flowrate through the valve 108 is open loop and wholly established by theprogramming of the master controller 130.

FIG. 2 illustrates a further embodiment of an HVAC system 200. This HVACsystem 200 is similar to the prior HVAC system 100 in that it includes avalve actuation arrangement 212 configured to cause valve 208, having aknown flow profile, to emulate a valve having a desired flow profile.However, this embodiment finds particular applicability for retrofittingexisting HVAC systems.

In this embodiment, the valve actuation arrangement 212 includes anintermediate signal translator device 220 interposed between valveactuator 222 and master controller 230. The intermediate signaltranslator device 220 is preferably an independent unit that can beinstalled into an existing system having an existing valve actuator 222and an existing master controller 230. The intermediate signaltranslator device 220 is configured to correlate the input controlsignal generated by the master controller 230 to an actual stempositional signal that is then sent to the valve actuator 222.

Thus, the intermediate signal translator device 220 would be programmedwith the lookup table discussed above. As such, in this embodiment, thecorrelation functions discussed with regard to valve controller 128would be provided by the intermediate signal translator device 220.

The intermediate signal translator device 220 will have an intermediatesignal translator device output interface that will cooperate with acorresponding actuator input interface of the valve actuator 222. Thesetwo interfaces are illustrated schematically by coupling 280. Thiscoupling 280 allows the intermediate signal translator device 220 to beoperably coupled to the valve actuator 224 and output the modified valvepositioning signal to the valve actuator 222. This arrangement allowsthe intermediate signal translator device 220 to be packaged as aseparate unit wholly independent of the valve actuator 222. In thisembodiment, the valve actuator 222 including its internal controller anddrive unit 224 would be a separate independent unit from theintermediate signal translator device 220.

The intermediate signal translator device 220 will also have anintermediate signal translator device input interface that willcooperate with a corresponding master controller output interface of themaster controller 230. These two interfaces are illustratedschematically by coupling 282. The plurality of interfaces andparticularly couplings 280, 282 allow for easily retrofitting anexisting system that only included master controller 230 and valveactuator 222 with the intermediate signal translator device 220 and thusbe configured to properly correlate the signal generated by the mastercontroller 230 based on a desired flow profile with a proper signalbased on the actual flow profile of the valve 208.

Again, intermediate signal translator device 220 may have numerouscorrelation mechanisms, i.e. lookup tables or mathematical equationsstored therein, such that it can operate in different modes as well asmay be user reprogrammable as discussed above.

FIG. 11 illustrates a further embodiment of an HVAC system 300. ThisHVAC system 300 is similar to the prior HVAC systems 100 and 200 in thatit includes a valve actuation arrangement 312 configured to cause valve308, having a known flow profile, to emulate a valve having a desiredflow profile when the desired flow profile is different than the knownflow profile of valve 308.

However, in this embodiment, the correlation from the input controlsignal to the actual stem positional signal is performed in the mastercontroller 330. The actual stem positional signal is then sent to thevalve actuator 322. The actual stem positional signal can be analog ordigital depending on the valve actuator 322 to which the mastercontroller 330 is attached. The master controller 330 may have separateinternal modules 331, 333. In the simplest form, the internal modules331, 333 could be separate subroutines performed by the mastercontroller 330. One module could be an input control signal module 331that generates an input control signal based on the desired flow profilelike in prior systems. However, prior to sending that input controlsignal to the valve actuator 322, the signal is sent to a translatormodule 333 that performs the correlation function and which generatesthe actual stem positional signal, which is subsequently sent to thevalve actuator 322.

Again, the master controller 330 is preferably reprogrammable as well asable to store more than one correlation mechanism, e.g. lookup table orequivalent mathematical equation, so that it can be operated in separatemodes based either on valves having different flow profiles or differentdesired flow profiles.

All references, including publications, patent applications, and patentscited herein are hereby incorporated by reference to the same extent asif each reference were individually and specifically indicated to beincorporated by reference and were set forth in its entirety herein.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) is to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. The terms “comprising,” “having” “including,” and “containing”are to be construed as open-ended terms (i.e., meaning “including, butnot limited to,”) unless otherwise noted. Recitation of ranges of valuesherein are merely intended to serve as a shorthand method of referringindividually to each separate value falling within the range, unlessotherwise indicated herein, and each separate value is incorporated intothe specification as if it were individually recited herein. All methodsdescribed herein can be performed in any suitable order unless otherwiseindicated herein or otherwise clearly contradicted by context. The useof any and all examples, or exemplary language (e.g., “such as”)provided herein, is intended merely to better illuminate the inventionand does not pose a limitation on the scope of the invention unlessotherwise claimed. No language in the specification should be construedas indicating any non-claimed element as essential to the practice ofthe invention.

Preferred embodiments of this invention are described herein, includingthe best mode known to the inventors for carrying out the invention.Variations of those preferred embodiments may become apparent to thoseof ordinary skill in the art upon reading the foregoing description. Theinventors expect skilled artisans to employ such variations asappropriate, and the inventors intend for the invention to be practicedotherwise than as specifically described herein. Accordingly, thisinvention includes all modifications and equivalents of the subjectmatter recited in the claims appended hereto as permitted by applicablelaw. Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the invention unlessotherwise indicated herein or otherwise clearly contradicted by context.

What is claimed is:
 1. A method of generating a correlation tableconfigured to correlate an input control signal to an actual stemposition signal for a valve having a known flow profile, the methodcomprising: receiving, from a user, a valve identifier identifying thevalve having a known flow profile; receiving, from the user, atheoretical flow profile identifier, the theoretical flow profileidentifier identifying a theoretical flow profile; and outputting, tothe user, a correlation table, wherein the correlation table isgenerated at a master controller using an input control signal and anactual stem positional signal, wherein the input control signal controlsa position of a valve stem operably coupled to the valve, the inputcontrol signal being generated at the master controller based on thetheoretical flow profile identifier that is other than the valveidentifier identifying the valve having a known flow profile, andwherein the actual stem positional signal is generated at the mastercontroller based on the input control signal and the known flow profileof the valve; and wherein the input control signal represents atheoretical valve stem position and the correlation table is generatedby identifying a theoretical flow rate corresponding to the theoreticalvalve stem position according to the theoretical flow profile,identifying a known valve stem position corresponding to the theoreticalflow rate according to the known flow profile of the valve, anddetermining the actual stem position signal corresponding to the knownvalve stem position.
 2. The method of claim 1, wherein receiving thetheoretical flow profile identifier comprises receiving user-definedtheoretical flow profile information.
 3. A method of controlling a valveactuator for a valve having a known flow profile, the method comprising:receiving an input control signal, the input control signal representinga theoretical valve stem position corresponding to a theoretical flowoutput generated based on a theoretical flow profile, the theoreticalflow profile being other than the known flow profile of the valve;correlating the theoretical flow output to a known valve stem positionaccording to the known flow profile of the valve and further correlatingthe known valve stem position to a known stem positional signal, theknown stem positional signal indicating a position of a valve stemoperably coupled to the valve that results in the theoretical flowoutput; and based on the correlation, generating the known stempositional signal.
 4. The method of claim 3, wherein the step ofreceiving the input control signal is performed by a linear signal.
 5. Amethod of operating a valve actuator arrangement for a valve having aknown profile, the method comprising: receiving, during a first mode, afirst valve stem control signal generated based on a theoretical flowprofile, the first valve stem control signal representing a firsttheoretical valve stem position; correlating, during the first mode, thefirst theoretical valve stem position to a first actual valve stemposition based on the known profile; correlating, during the first mode,the first actual valve stem position to a first actual valve stempositional signal based on the known profile; generate, during the firstmode, the first actual valve stem positional signal based on thecorrelation of the first actual valve stem positional signal to thefirst actual valve stem position; and adjust, during the first mode, aposition of the valve based on the first actual valve stem positionalsignal, wherein the adjustment facilitates first theoretical flowcharacteristics associated with the theoretical flow profile for thevalve.
 6. The method of claim 5, further comprising: receiving, during asecond mode, a second valve stem control signal generated based on thetheoretical flow profile, the second valve stem control signalrepresenting a second theoretical valve stem position; correlating,during the second mode, the second theoretical valve stem position to asecond actual valve stem position based on the known profile;correlating, during the second mode, the second actual valve stemposition to a second actual valve stem positional signal based on theknown profile; generate, during the second mode, the second actual valvestem positional signal based on the correlation of the second actualvalve stem positional signal to the second actual valve stem position;and adjust, during the second mode, the position of the valve to anotherposition based on the second actual valve stem positional signal,wherein the adjustment facilitates second theoretical flowcharacteristics associated with the theoretical flow profile for thevalve.
 7. The method of claim 6, further comprising: dynamicallyswitching from the first mode to the second mode to achieve thetheoretical flow characteristics.